// type str = string
// let c: str = '123'

// type test = string | number

// let d: test = '123'
// let e: test = 12
// let f: test = false

let c: string = 'yyy'

type str = 'xxx' | 'yyy' //字符串字面量类型
type status = 0 | 1 //数字字字面量类型

// let d: str = 'abc'
let e: status = 2
